Football shoes provide a variety of functions that are specifically adapted to the needs of football. A particularly important function of a football shoe is to provide a good grip between the upper of the shoe and a ball. By means of an increased grip of the ball at the upper, an improved control of the ball may be achieved.
By means of the increased grip, the ball may be provided with a particular spin when shooting, passing or free-kicking which allows specific trajectories of the ball. The greater the grip of the ball by the upper, the more spin that can be transferred to the ball.
In addition, an increased grip of the ball at the upper may also be advantageous for dribbling. In particular, it may allow the ball to follow fast movements of a foot more easily and it may allow a more precise ball control by the foot since the ball is prevented from sliding off the upper. In particular, in wet conditions, such an increased grip between ball and upper is desirable.
Usually, football players use specific areas of the upper of a football shoe for different types of contact with the ball, for which correspondingly varying degrees of grip are desirable. Therefore, the different areas of a football shoe should be provided with different grip properties.
Various football shoes are known in the prior art which provide an upper with locally increased grip. To this end, the upper of the shoe is typically equipped with a particular profile or with particular profile elements.
In this context, it turned out that rubber is particularly suited for profile elements to provide an increased grip between the upper of a football shoe and a football. Rubber enables a considerably better grip than other materials, as for example thermoplastic polyurethane (“TPU”). The grip properties of rubber, in addition, are also substantially maintained in wet conditions.
A football shoe comprising an area of the upper which is adapted for an improved ball control is known from document WO 2001/078540. This area provides an improved elasticity and grip. The increased grip is provided by a plurality of flat rubber elements, which are sewn to an elastic material which provides the increased elasticity. Alternatively, they are chemically bonded to the latter.
Also from document WO 2004/093588, a football shoe comprising an area of the upper that is provided for an increased ball control is known. The area comprises rubber elements which are attached to the area. Alternatively, the rubber elements may be removably attached to the upper or integrally formed with the upper.
From document WO 2002/054898, rubber elements are known that are attached to an inner layer of the upper and that are subsequently sewn to an outer layer of the upper. According to WO 2002/054898, alternatively, it would be advantageous to attach the rubber elements to a fabric, which may then be attached to the upper.
The sewing of a profile element, which is known from the specified prior art documents in multiple ways, is very labor-intensive and, in addition, only allows for large elements. Moreover, a seam may lead to pressure marks on the foot. Also, attaching profile elements to a fabric, which is subsequently attached to an upper, is very cumbersome. Moreover, the additional use of fabric unnecessarily increases the weight and the cost of the shoe. An integral design of the elements and the upper leads to the disadvantage that the materials that are used for the upper and the individual elements, respectively, cannot be independently optimized. Typically, it is desirable that the materials of the upper comprise different properties than the profile elements. For example, materials for the upper should be breathable and abrasion-resistant.
All cited documents, additionally, have the collective disadvantage that without sewing a sufficiently strong connection between the profile elements and the upper, which may resist the large forces that occur at the upper of the shoe when playing football, may not be achieved. If the profile elements are only glued to the upper, they will fall off very quickly and, therefore, the increased grip of the upper is lost very quickly.
From document GB 940,925, it is known that a rubber layer with protrusions may be arranged within an upper of a football shoe, wherein the upper provides openings at the positions of the protrusions, through which the protrusions may extend. However, this requires a continuous layer of rubber, which reduces the breathability of the upper and also unnecessarily increases the weight and material costs of the upper.
As a result, the methods known in the prior art that may be used for connecting profile elements comprising rubber material to an upper for a shoe, in particular a football shoe, are limited. Sewing is labor-intensive and therefore expensive. In addition, it restricts the design freedom, as well as the functionality of the profile elements, since these have to comprise a specific minimum size such that they may be sewn. The alternative methods for attaching do not allow a sufficiently strong connection of profile elements comprising rubber material.
From document U.S. Pat. No. 4,447,967, a method is known in which plastic material is directly injected onto an upper, in order to strengthen the upper. When compared to rubber material, however, only very weak grip may be obtained from the use of such materials, which is particularly weak in wet conditions.
Document CN 22 96 643 Y discloses a pair of rubber-faced sports shoes, wherein rubber sheets with concave and convex colloidal particles are fixed to the upper surfaces of sports shoes, and may be pasted on the front ends of the sports shoes by hot pressing or glue.
Document WO 83/03339 A1 discloses an item of footwear having an upper provided with an external area of an elastomeric material. The elastomeric material is a soft or synthetic rubber, may be a smooth or non-smooth (e.g. dimpled) surface, and may be affixed to the footwear item by adhesive or by vulcanizing.
Document DE 1 902 266 A discloses a football shoe coated entirely with a rubber layer having a patterned surface. The upper is manufactured by inserting into a forming device that is covered with a raw rubber compound. The material is vulcanized in a closed manner by means of a pressing plate with a patterned surface.
Document GB 2 259 639 A discloses an article of footwear, e.g. a football boot, having at least one region/zone at which frictional interaction during contact between a ball and the region/zone is enhanced. The regions/zones can be provided by attaching a panel of a material comprising a backing layer that to be secured by suitable adhesive, stitching etc.
Document US 2012/0066931 A1 discloses a bonded mesh composite panel that can be used to form a three-dimensional upper shell that includes extensions used for double-lasting and/or to provide a shelf to support foam padding, e.g. a midsole.
Document EP 0496 931 A1 discloses a covering element applicable to items of footwear for soccer, which comprises a body made of a substantially elastic material that defines a cavity for the insertion at least of the front portion of a soccer shoe.
It is therefore desirable to provide an improved method for manufacturing an upper for a shoe, in particular a football shoe, which comprises good grip properties.